The present invention relates to metal, and more particularly relates to metal containing desired amounts of oxygen, such as metal oxide materials.
It has been found that oxygen enriched metal substrates offer some advantages over their pure metal counterparts. For example, capacitors made from oxygen enriched Nb have low leakage current and are less sensitive to contaminates such as carbon. It is proposed that the presence of oxygen reduces the contamination level via oxidation during the high temperature manufacturing process. Though air or controlled atmosphere exposure can introduce oxygen into a metal substrate, precise control of the process is far from simple. This results from the fact that many metal substrates, especially those in a high surface area powdery form are highly reactive and the oxidation tends to be localized, which makes controlled oxidation difficult.
Furthermore, the benefits of valve metal suboxides, such as niobium suboxides, in such applications as capacitor anodes has been shown to be useful. In a typical process, niobium metal powder, for instance, is mixed with niobium pentoxide and heat treated to form a desired niobium suboxide such as NbO. In the product made by this method, the physical structure of the raw materials typically remains. The residual niobium pentoxide structure, which can have a fine microstructure, may inhibit to some extent the impregnation steps in forming the finished capacitor. While the current method of forming valve metal suboxides is very beneficial and provides many advantages over standard capacitor anodes, methods to better improve the overall pentoxide and its use in an anode would be beneficial.